Prevent slow graceful restarts on some platforms:

* prefork.c (ap_mpm_run): Only make as many dummy connections as slots
used, not as many as slots are available.

Backport of server/mpm/prefork/prefork.c r1.280 from httpd-2.1
Reviewed by:	Joe Orton, Jeff Trawick, Justin Erenkrantz


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@102115 13f79535-47bb-0310-9956-ffa450edef68